Cylinder lock

ABSTRACT

A LOCK MECHANISM COMPRISING A CYLINDRICAL SHELL HAVING A TUMBLER ENGAGING MEANS THEREON AND ADAPTED TO RECEIVE A PLUG MEMBER THEREIN FOR RELATIVE ROTATIONAL MOVEMENT WITH RESPECT TO THE SHELL. THE PLUG IS ADAPTED TO CARRY A PLURALITY OF TUMBLER MEMBERS WHICH MOVE INTO AND OUT OF LOCKING ENGAGEMENT WITH THE SHELL IN RESPONSE TO INSERTION AND WITHDRAWAL OF A KEY TO THUS PERMIT RELATIVE ROTATION OF PLUG IN SHELL WHEN THE KEY IS INSERTED AND TO RESTRAIN SUCH MOVEMENT WHEN THE KEY WITHDRAWN.

Jan. 19, 1971 N. L. BERKown'z "If i CYLII IDER LOCK Filed Nov. 12, 1968 5 Sheets-Sheet 1 Q 2 v/m/mzfor Zy Wax/m 969%0wq 1 .9, EQF/fi Q 's Kown'z CYLINDER LOCK Hind Nov, 12 1968 5 Shasta-Sheet 2 m wrzey 1971 N. L; BERKowrrz 8,553,

CYLINDER LOCK Filed Nov. 12, 1968 5 Sheets-Sheet S WM pM/MM/L 3 1971 N. L. BERKOWITZ CYLINDER LOCK Filed Nov. 12, 1968 5 Sheets-Sheet A Wmaz 722%?0M/Z3 Q paw/1m w, 1971 N. L. BERKOWITZ 3,

cvmmmn LOCK Filed Nov. 12, 1968 5 Sheets-sheaf? United States Patent 3,555,859 CYLINDER LOCK Nathan L. Berkowitz, 4762 N. Cumberland Blvd., Milwaukee, Wis. 53211 Continuation-impart of application Ser. No. 658,831, Aug. 7, 1967. This application Nov. 12, 1968, Ser. No. 778,915

Int. Cl. Eb 15/14 U.S. Cl. 70-340 21 Claims ABSTRACT OF THE DISCLOSURE A lock mechanism comprising a cylindrical shell having a tumbler engaging means thereon and adapted to receive a plug member therein for relative rotational movement with respect to the shell. The plug is adapted to carry a plurality of tumbler members which move into and out of locking engagement with the shell in response to insertion and withdrawal of a key to thus permit relative rotation of plug in shell when the key is inserted and to restrain such movement when the key is withdrawn.

This application is a continuation-in-part of application Ser. No. 658,831 filed Aug. 7, 1967, and now abandoned.

BACKGROUND OF THE INVENTION (-1) Field of invention This invention relates to multiple tumbler cylinder locks.

(2) Description of the prior art For many years prior to this invention and at the present time, cylinder locks of conventional design employed a plurality of separate springs (usually coil-type compression springs) to bias the lock tumblers. Inherent in such multiple separate spring arrangements are problems of poor alignment causing breakage and mislocation as well as assembly problems. Alternate constructions designed to eliminate the shortcomings of the conventional multiple separate spring arrangement have been attempted, but for various reasons have met with only limited success (see US. Pat. 1,664,404).

The principal object of this invention is to provide an improved construction which eliminates the shortcomings of the separate spring arrangement and at the same time provides a substantially trouble-free and compact design employing a relatively few, simple and inexpensive parts which cooperate to provide a lock mechanism capable of providing a large number of different key combinations and a simplified master key arrangement.

SUMMARY OF INVENTION The lock mechanism of this invention is comprised of a cylinder shell having a pair of tumbler engaging slots therein and a cylinder plug mounted in the shell and adapted for relative rotation movement with respect thereto. A plurality of individual tumbler members are mounted in aligned openings in the plug, each of which is provided with a locking tongue adapted for movement into and out of locking engagement with the cylinder shell. Each tumbler is provided with a curved spring arm and a centrally depending key actuated portion having a regular key bearing surface formed thereon for engagement by the cam surface of a key to thus impart an unlocking movement to the tumbler. The unlocking movement of the tumbler will flex the tumbler spring arm from a condition of lower stress to a condition of higher stress. The curvature of the spring arm conforms substantially to that of the inside wall of the shell and when flexed by the key moves from a greater to a lesser radius of curvature.

Patented Jan. 19, 1971 The tumbler spring arm can be made integrally with the tumbler or may be made from a separate part to utilize a material of greater resiliency. If the integral construction is employed, the tumbler is preferably made from a stamping with the spring arm specially formed by a reducing operation to produce the desired strength and resiliency. In either construction, the conventional separate spring arrangement is eliminated to provide a greatly simplified, more compact arrangement.

In addition to the regular key bearing surface on each of the tumblers, a second independent master key bearing surface is provided adjacent the regular key bearing surface. Thus, since the master key and regular key bearing surfaces are completely independent, a given master key can be used to operate an entire series of locks requiring different regular key combinations.

Other objects and advantages will be pointed out in or be apparent from the written description and claims, as will obvious modifications of the several embodiments shown on the drawings.

FIG. 1 is an exploded perspective view of a lock mechanism incorporating one embodiment of the invention;

FIG. 2 is a top plan view of the lock mechanism of FIG. 1 but shown in assembled position;

FIG. 3 is a front end elevation view of the lock mechanism shown in FIG. 2;

FIG. 4 is a sectional view taken along the line 44 of FIG. 2;

FIG. 5 is a sectional view similar to FIG. 4, but with the key inserted into the lock mechanism;

FIGS. 6 and 7 are sectional views taken along lines 6-6 and 77, respectively, of FIG. 4;

FIG. 8 is a sectional view taken along line 88 of FIG. 5;

FIG. 9 is an exploded perspective view of a lock mechanism incorporating a second embodiment of the invention;

FIG. 10 is a sectional view of a typical regular key used with the lock mechanism of the invention taken along line 10-'10 of FIG. 19;

FIG. 11 is a sectional view of a typical master key used with the lock mechanism of the invention taken along line 1111 of FIG. 20;

FIG. 12 is a side view of a torsion tumbler member of modified design;

FIG. 13 is a perspective view of a torsion tumbler member of modified design;

FIG. 14 is a longitudinal sectional view of the second embodiment (FIG. 9) with the parts in assembled position and with the key inserted therein;

FIG. 15 is a longitudinal sectional view similar to FIG. 14, but with the key removed;

FIGS. 16 and 17 are sectional views taken along lines 1616 and 1717, respectively, of FIG. 15;

FIG. 18 is a sectional view taken along line 18-18 of FIG. 14;

FIG. 19 is a partial side elevation view of a typical regular key used with the lock mechanism of the invention;

FIG. 20 is a partial side elevation view of a typical master key used with the lock mechanism of the invention; and

FIGS. 21, 22 and 23, 24 are side and end views of a preferred form of torsion tumbler showing the tumbler before and after the spring arm thereof has been formed by a reducing operation.

Referring to the drawings in detail wherein like parts are given like reference numerals, FIG. 1 shows an ex- 3 ing cylindrical cavity 11 adapted to receive a subassembly comprising a cylinder plug 12, a cylinder cap 14, a cylinder cam 16, a plurality of torsion tumbler members 18a, 18b, etc. and a pair of torsion tumbler anchoring bars 20, 20.

Cylinder plug 12 in its preferred form is made from a flat metal stamping which is bent into a substantially U-shape having legs 22, 22. The tips of each leg of the U are bent over as indicated by reference numeral 24 to provide a substantially circular flange on which cylinder cap 14 can be securely mounted.

The legs 22 of plug 12 are provided with two sets of aligned openings 26 and 28 of rectangular shape in which torsion tumblers 18a, 18b, etc. are mounted as will be explained hereinafter. The cylinder plugs shown in FIGS. 1 and 2 are of substantially identical construction except that the FIG. I plug has four (4) sets of aligned openings 26, 28 and the FIG. 2 plug has seven (7).

Torsion tumblers 18a, 18b, etc. are of novel design and as shown in FIG. 1 are of substantially G-shape when viewed from the inner end of the lock mechanism. The plurality of torsion tumblers employed are of substantially identical construction with the exception of the particular configuration of the key actuated portion of each tumbler as will be explained in detail hereinafter. The tumblers 18a, 18b, etc. shown in FIG.1 are of one-piece construction. Each tumbler is comprised of a centrally depending key actuated portion 34, a locking tongue portion 36 formed at one end of portion 34, a curved spring arm 32 formed on said central portion 34 and extending from the same end thereof at which said locking portion 36 is located and a retaining lip 30 formed at the end of spring arm 32. Spring arm 32 is curved to substantially conform to the cylindrical inner wall of cavity 11 of shell 10. The key actuated portion 34 is cut out as at 38 to provide a continuous slot into which a key 40 can be inserted. At one end of cut-out portion 38 opposite locking tongue 36, a key bearing surface 42a (42b, etc.) is provided for engagement by one of the cam surfaces 44a, 44b, etc. on key 40 (FIG. to thereby actuate locking tongues 36 from lock to unlock position against the bias of spring arms 32 as will be explained in greater detail hereinafter. It should be noted at this point that cut-out portions 38 are of constant length and that key bearing surfaces 42a, 42b, etc. are located at different positions relative to the center line of the key and can thus be adapted for selective actuation by a particular key cam surface 44a, 44b, etc.

Cylinder cam 16 is of substantially disk-shape having a pair of oppositely facing notches 46, 46 in the edge thereof for retaining the rear ends of spring bars 20, 20.

Spring bars are of elongated configuration having a central retaining bar portion 48 adapted for engagement by retaining lips of tumblers 18a, 1817, etc. A cross arm portion 50 is provided on the inner end of each bar 20 for engagement with the rear face of cylinder cam 16 adjacent notches 46, 46 and the front ends of bars 20 are bent inwardly as at 52 for retention adjacent plug 12 by cap 14. Cylinder cap 12 is provided with a keyway 54 to allow insertion of key into the lock mechanism.

To assemble the lock mechanism, a plurality of torsion tumbler members of known key bearing surface configuration are selected and mounted in aligned openings 26, 28 of cylinder plug 12. Tumblers in adjacent openings are inverted one with the other with the locking tongue 36 of one extending outwardly from plug 12 in the opposite direction from that of the other. Similarly, the retaining lip 30 of one tumbler will be engaged by the spring bar 20 on one side of the plug, while the retaining lip of the next adjacent tumbler will be engaged by the spring bar on the opposite side. The key actuated portions 34 of all tumblers are positioned for radial movement in the respective plug openings with the bearing surfaces of one tumbler adapted for engagement by a cam surface on one edge of the key and the bearing sur- 4 face of the next adjacent tumbleradapted for engagement by a cam surface on the opposite edge of the key. While the FIG. 1 embodiment shows the tumblers in adjacent openings inverted one with the other, it should be understood that if desired some tumblers could be positioned for actuation in the same direction.

The tumblers and spring bars are held securely in assembled position between cylinder cam 16 and cylinder cap 14 with the cap inserted over the ends 52 of spring bars 20 and the front end portions 24 0f plug 12 after the parts have been assembled. The key is then inserted into the plug subassembly to retract the locking tongues 36 and the entire subassembly can then be inserted into I the cylinder shell 10 as shown in FIG. 2. As thus shown,

removal of the key will allow the locking tongues to be biased outwardly for engagement in slots 56, 56 in shell 10 to thus restrain relative rotation of the plug and shell.

It should be noted at this pointthat in addition to regular key bearing surfaces 42a, 42b, etc. provided on tumblers 18a, 18b, etc., such tumblers are provided with master key bearing surfaces 60a, 60b, etc. Such surfaces of adjacent tumblers are offset with each other and are designed for actuation by a master key 62 having a cross-section configuration like that shown in' FIG. 11; As there shown the master key is provided with cam portions 64a, 64b, etc. which are offset one with the other to thus make contact with bearing surfaces 60a, 60b, etc.

A second embodiment of the present invention is shown in FIGS. 9, 14, 15, 16, 17 and 18. In this embodiment, the cylinder shell, cylinder plug and cylinder cap are similar to that shown in FIG. 1 and are thus identified with the same reference numerals. The principal difference between the FIG. 1 and the FIG. 9 embodiments is the construction of tumbler members 66a, 66b, etc. and the mounting arrangement therefor. Such members are comprised of a centrally depending key actuated portion 70, a pair of oppositely extending locking tongue portions 72, 74 formed at opposite ends of said portion 70 and a curved spring arm 68 extending from one end of said central portion 70, Each key actuated portion 70 is provided with adjacent regular key and master key bearing surfaces 76a, 76b, etc. and 78a, 78b, etc. The parts are assembled in a manner similar to that described with respect to FIG. 1 above. The primary difference is that in this embodiment pairs of oppositely acting tumblers 66a, 661;, etc. are mounted in each pair of aligned openings 26 and 28 of plug 12 and also no spring bars 20 are required. Spring arms 68 of tumblers 66a, 66b, etc.'

are curved to substantially conform to the curvature of the wall of cylindrical cavity 11 of shell 10 and such arms are positioned to bear against and be restrained directly by the surface of cavity 11 as shown in FIG. 16 with locking tongues 72 thereof extending into slots 56, 56. As shown in FIGS. 14 and 18, when key 80 is inserted, key actuated portions 70 of the tumblers will be actuated radially causing locking tongues 72 to be retracted out of engagement with slots 56, 56 of shell 10. Such retract ing movement will cause spring arms 68 to be flexed by the J restraining action of cavity 11 to thus create a spring action tending to urge locking tongues 72 radially out-, wardly towards lock position. Such flexure of arms 68 extends for at least of the arm curvature. Using the inside surface of shell 10 to restrain arms 68 provides a plug 12 and shell 10-. As clearly shown in FIG. 14, when the tumblers are properly actuated to unlock position,

locking tongues 74 will be positioned a short distance out of engagement with slots 56, 56 to thus permit free relative rotation of the plug and shell. It will be appreciated, however, that if any tumbler is moved a greater distance than is necessary for tongues 72 to just clear slots 56, tongues 74 will move into locking engagement with slots 56 and prevent relative movement of plug and shell. This feature makes it impossible to actuate the parts to unlock position by a blank key, that is to say, it makes it more difficult to pick the lock.

FIGS. 12 and 13 are examples of alternate tumbler constructions which may be employed to advantage. The FIG. 12 type tumbler 82 is similar to tumblers 66a, 66b shown in FIG. 9, and is comprised of a curved spring arm 84, a centrally depending key actuated portion 86 and a pair of oppositely extending locking tongues 88, 89. Spring arm 84, however, is not made integral with the rest of the tumbler, but is made of a separate part attached to the body of the tumbler in any suitable manner such as the staked tongue and groove arrangement 90 shown in FIG. 12. This two-piece tumbler construction permits use of a spring arm 84 made from an extremely resilient material such as spring steel compared to that of the tumbler body to thus improve the biasing characteristics of the tumbler.

The FIG, 13 type tumbler 92 is also of the same general type as that shown in FIG. 9. It is of one-piece design comprising a spring arm 94, a key actuated portion 96 and locking tongues 98, 100. Portion 96 and tongues 98, 100 are comprised of a double layer of material made by bending the parts over on themselves. This construction provides added strength and wearing surface in the areas engaged by the key and at the same time provides a spring arm of lesser gauge for greater resiliency.

FIGS. 21-24 show another tumbler design which pro vides some significant advantages over other designs. FIGS. 21 and 22 show a tumbler 102 in its initial stage of manufacture. As thus shown, the tumbler 102 is of similar configuration to the tumblers 66a, 66b, etc. shown in the FIG. 9 embodiment and is comprised of a key actuated portion 104, a pair of oppositely extending locking tongues 106, 108 and a curved spring arm 110. The tumbler 102 as shown in FIGS. 21 and 22 is preferably in the form of a metal stamping.

To complete the manufacture of tumbler 102, the spring arm 110 of the stamping is subjected to a. reduction operation by either hot or cold working to reduce the thickness of the arm and thereby produce a finished tumbler like that shown in FIGS, .23 and 24. Preferably such reduction is accomplished by subjecting the spring arm to a hot rolling operation. As thus shown, the reduction operation performed on the spring arm 110 will produce a finished spring arm 112 having a reduced thickness and an increased width. Such reduction of the spring arm changes the physical characteristics thereof to both increase its resiliency and its strength and thus provide a tumbler having a substantially increased service life while at the same time maintaining it within the required size limitations.

OPERATION The operation of the lock mechanism can best be described by reference to FIGS. 4-8. FIGS. 4, 6- and 7 show the parts in locked position with tumblers 18a, 18b, etc. in unstressed (or prestressed) condition and with tongues 36 extending into slots 56 of shell 10 to thus lock the plug and shell together.

To actuate the parts to unlock position, key 40 is inserted all the way into the plug to the position shown in FIG. 5. As can be readily understood by a comparison of FIGS. 6 and 8, the insertion of the key as aforesaid will bring cam surface 44a thereon into engagement with bearing surface 42a on tumbler 18a. The camming action of the key will cause key actuated portion 34 of the tumbler to move from the position shown in FIG. 6 to that shown in FIG. 8. The movement of portion 34 will be substantially vertical as viewed in the drawings due to the restraining action of legs 22 of plug 12 which serve as vertical guides for locking tongues '36 to thus restrain any tendency of the actuated portion 34 to pivot inside the plug when the key is inserted therein. This unlocking movement of portion 34 will bend or flex spring arm 32 of the tumbler from a condition of lower stress (FIG. 6) to a condition of higher stress (FIG. 8) wherein the arm has a reduced radius of curvature. Spring arm 32 thereby serves to bias the locking tongue into its locked position. During these movements of the tumbler, it is anchored at one point by spring bar 20 and will slide against one face of plug leg 22 at surface 58'. It will be appreciated from the foregoing that the movement of the tumblers will be substantially free of frictional forces.

Moving now to the next adjacent tumbler 18b towards the rear (FIG. 7), such tumbler is positioned in an inverted position with respect to that shown in FIG. 6. This tumbler 18b will be actuated by key 40 in substantially the same manner as was tumbler 18a except that its bearing surface 42b is dimensioned for actuation by cam portion 44b on key 40 to thereby move its locking tongue 36 from lock to unlock position.

The remaining tumblers 18c,i18d, 18c, 18], etc. operate in the manner described above with respect to tumblers 18a, 18b. Thus as shown in FIG. 5, when key 40 is inserted into the lock each tumbler will be actuated to thereby retract all looking tongues 36 from slots 56, 56 of shell 10 to thus permit free relative rotation between plug 12 and shell 10. Removal of key 40 will permit locking tongues 36 on the tumblers to return to the lock position shown in FIG. 4 due to the spring biasing force exerted by spring arms 32 of each tumbler.

The lock mechanism is operated by master key 62 in essentially the same manner as with the regular key 40. Insertion of master key 62 into the lock will cause cam surfaces 64a, 64b, etc. thereof to make operative engagement with master key bearing surfaces 60a, 60b, etc. which in turn will actuate tumbler tongues 36 from lock to unlock position. It will be appreciated that since the master key and regular key bearing surfaces are independent from each other, a given combination of master key surfaces 60a, 60b, etc. can be maintained through an entire series of different regular key combinations and thus a single master key can be used to open a large number of locks having different regular key combinations.

Referring now to the operation of the lock mechanism shown in FIG. 9, to actuate the parts to unlock position, key is inserted all the way into the plug to the position shown in FIG. 14. Such insertion of the key will actuate tumbler 66 for example, from the position shown in FIG. 16 to that shown in FIG. 18. This unlocking movement of the tumbler will move spring arm 68 from a condition of lower stress to a condition of higher stress wherein its radius of curvature will be reduced due to the combination of the force applied at bearing surface 769 and the restraining action exerted on the arm by the inside surface of cavity 11 in shell 10. Just as in the FIG. 1 embodiment described above, the next adjacent tumbler 66s is positioned in an inverted position and adapted for actuation in the opposite direction by a cam surface on the top edge of key 80 as viewed in FIG. 14. By mounting two tumblers in each pair of plug openings a more compact arrangement results.

The remaining tumblers operate in the manner described above with respect to tumblers 66], 662. Thus as shown in FIG. 14, when key 80 is inserted into the lock, each tumbler will be actuated to thereby retract all locking tongues 72 from slots 56, 56 of shell '10 to thus permit free relative rotation between plug 12 and shell 10. As stated previously, proper actuation of the tumblers will disengage tongues 72 from slots 56 but will not cause tongues 74 to become engaged with the slots. If, however, any one of the tumblers is actuated for a greater distance than is necessary to just disengage tongues 72, tongues 74 will move into locking engagement with slot 56 to thus prevent relative rotation of plug and shell. As previously explained, this feature makes it more difficult to pick the lock.

It will be apparent from the foregoing description that the number of dilferent key combinations which can be provided by the lock mechanism of FIG. 1, for example, will depend on the number of tumblers 18a, 18b, 180, etc. used and the number of dilferent key bearing surfaces 42a, 42b, 42c, etc. provided for such tumblers. For example, if eight (8) tumblers are used each having four (4) diiterent key bearing surfaces, over one million different key combinations can be utilized. It will be appreciated, therefore, that an extremely large number of combinations can be provided with a very compact construction utilizing a relatively small number of simple, easily manufactured parts.

It will also be appreciated that elimination of the conventional coil-type compression springs for biasing the tumblers not only provides greater reliability at reduced cost and size, but increases the amount of internal clearances to facilitate movement of dirt and foreign particles through the mechanism to thus reduce sticking of the parts when the key is inserted or removed.

The spring arm arrangements for biasing the tumblers are designed to provide a relatively low spring coeflicient, i.e., ratio of actuating force to distance moved. In the FIG. 1 embodiment where the tumbler is restrained at two points, the effective length of the spring arm is about 180. In the FIG. 9 embodiment where the tumbler is restrained by the inside wall of the shell, the effective length of the spring arm is in excess of 90.

In both embodiments the mechanism can be actuated with a minimum amount of force to thus reduce wear and provide smooth reliable operation.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention.

I claim 1. A lock mechanism comprising:

a shell having a cylindrical cavity wall therein;

a plug mounted in said cavity wall and adapted for relative rotational movement with respect to said shell;

tumbler means including a plurality of tumbler members operatively associated with said plug, each tumbler having a locking portion thereon adapted for movement into and out of locking engagement with said shell;

spring means for biasing said tumblers in one direction, said spring means including a curved spring arm mounted on each tumbler, said curved spring arms having a variable radius of curvature, the curvature of said arms conforming to the curvature of said cylindrical cavity wall over the entire length of said arms; and

means including a key member for actuating said tumbler members from lock to unlock possition and for flexing said arms from a condition of lower stress to a condition of greater stress wherein the radius of curvature of said arms is reduced as said tumbler members are actuated from lock to unlock position.

2. A lock mechanism according to claim 1 in which each of said spring arms of said spring means is integral with said tumblers and when actuated will flex for at least 90 degrees of its curvature.

3. A lock mechanism according to claim 1 in which said spring arms of said spring means make contact with said cavity wall and are restrained thereby when said tumblers are actuated by said key.

4. A lock mechanism according to claim 1 in which said spring arms are made from a separate part attached to said tumblers and of a material of greater resiliency than that of said tumblers.

5. A lock mechanism according to claim 1 in which said tumblers of said tumbler means are positioned in 8 side-'by-side relationship and adjacent tumblers are adapted for actuation in opposite directions by said key.

6. A lock mechanism according to claim 1 in which said tumblers of said tumbler means are comprised of a centrally depending key actuated portion having said locking portion formed at one end thereof and said spring arm extending therefrom at the same end thereof.

7. A lock mechanism according to claim 1 in which each of said spring arms is an integral part of said tumblers, said tumblers being made of a metal stamping with the material of the spring arms thereof having a greater resiliency than the remaining portion of saidtumblers.

'8. A lock mechanism comprising:

a shell means having a tumbler engaging means thereon and cylindrical cavity wall therein;

a plug assembly means mounted inside said cylindrical cavity wall and adapted for relative rotational movement with respect to said shell;

a plurality of tumbler members movably mounted in said plug assembly and adapted for movement into and out of locking engagement with said tumbler engaging means of said shell, each of said tum'bler members having a curved spring arm mounted thereon and extending therefrom in the same plane therewith, the curvature of said arms conforming to the cylindrical shape of said cavity wall over the entire length of said arms; and

means including a key member for actuating said tum- =bler members from lock to unlock position and for flexing said arms from a condition of lower stress to a condition of greater stress as said tumblers move into and out of locking engegement with said tumbler engaging means of said shell.

9. A lock mechanism according to claim 8 in which said tumbler spring arms of said spring means are integral with said tumblers and when actuated will flex over at least degrees of its curvature.

10. A lock mechanism according to claim 8 in which said tumbler members of said tumbler means include a centrally depending key actuated portion having a key bearing surface thereon adapted for engagement by said key and further having a locking tongue formed at one end thereof, said spring arms extending from said centrally depending key actuated portion at a point adjacent said locking tongue.

11. A lock mechanism according to claim 8 in which said curved spring arms of said spring means are in contact with said cavity Wall and are restrained thereby when said tumblers are actuated by said key.

12. A lock mechanism according to claim 8 in which said tumbler members are metal stampings and said tumbler spring arms are an integral part of said tumblers, the material of said spring arms having a greater resiliency than the remaining portion of said tumblers.

13. A lock mechanism comprising:

a shell means having a tumbler engaging means thereon and a cylindrical cavity Wall therein;

a plug assembly means mounted in said cylindrical cavity wall and adapted for relative rotational movement with respect to said shell;

a plurality of tumbler members movably mounted relative to said plug assembly and adapted for movement into and out of locking engagement with said tumbler engaging means of said shell, each of said tumbler members having a curved spring arm integral therewith, the curvature of said spring arms sub-' stantially conforming to the shape of said cavity wall and are in contact with said wall, said wall serving to restrain said arms causing them to flex as said tumblers move into and out of locking engagement with said tumbler engaging means of said shell; and p a key member adapted when inserted intosaid plug assembly to actuate said tumblers from lock to unlock position.

14. A lock mechanism according to claim 13 in which said cylinder plug is made from a metal stamping bent into a substantially U-shape with the legs of the U having pairs of aligned openings in which said tumbler members are mounted.

15. A lock mechanism according to claim 14 in which two tumbler members are mounted in each pair of aligned openings in said cylinder plug, one of said two tumblers adapted for actuation in one direction and the other of said tumblers adapted for actuation in the opposite direction.

16. A lock mechanism according to claim 13 in which each of said tumbler members further includes a key actuated portion having a regular and a master key bearing surface formed thereon, said regular key bearing surface located on the center line of said plug and said master key bearing surface being located offset from the center line of the plug.

17. A lock mechanism according to claim 16 in which said key actuated portion of each tumbler is made from a double layer of material and each spring arm is made from a single layer of material.

18. A lock mechanism according to claim 13 in which each of said tumbler members further includes a locking tongue formed thereon with said spring arms extending from a point adjacent said locking tongues.

19. A lock mechanism according to claim 13 in which the material of each of said curved spring arms is of 21. A lock mechanism according to claim 8 in which said curved spring arms flex from a position of greater radius to a position of lesser radius as said tumblers are actuated from lock to unlock position.

References Cited UNITED STATES PATENTS 1,218,065 3/1917 Diesel 70-364 1,431,735 10/ 1922 Freysinger 70-3 64 1,644,092 10/ 1927 Shonn 70364 1,664,404 4/1928 Douglas 7 0--364 1,860,708 5/ 1932 Falk 70364 1,957,851 5/1934 Rubner 70340 2,206,539 7/ 1940 Swanson 70-3 64 MARVIN A. CHAMPION, Primary Examiner R. L. WOLFE, Assistant Examiner US. Cl. X.R. 70364, 377 

